5C-Factors affecting the rate of photosytehnsis

Question 1

What are the 7 factors that affect photosynthesis

Answer 1

1. Light intensity
   2.Wavelength of light
   3.Temperature
   4.PH
   5.CO2 concentration
   6.Water avabiltiy
   7.Enzyme inhibition

Question 2

How does light intensity affect the rate of photosynthesis

Answer 2

Rate of photosythensis increases as light intensity increases bcause light dependent reactions can take places,
but only increases until the point of saturaiton

Question 3

What happens when the maximum rate of photosynthesis is reached,rate of phootyshtensis without icnrease or decrease just remains constant

Answer 3

Once the maxiumum rate of photosytehnsis occurs, a plateau occurs where all the enzymes in the chloroplasts are saturated.

Question 4

After point X of the light intensity-rate of photosythensis diagram, what becomes the limiting factor

Answer 4

Temperature, water or carbon dioxide

Question 5

Why does the rate of photosythensisn increase a slight intensity increases towards point X

Answer 5

The increase in the rate of photosythensis towards point X as light intensity increases is due to the plant being exposed to greater light energy, which is absorbed by chlorophyll withijn within many more plant cells, Light breaksn co2
and h2o for photosynthesis to happenthus increasing overall photosythensis.

Question 6

What happens after the point of saturation-point X and why does this happen

Answer 6

The rate of photosythensis plateausbecause the enzymes in the chloroplast become saturated but rate of photosyhtensis is still occuring at a high rate but the rate is not no longer increasing OR dueto limiting factors

Question 7

A plateau on a graph can be caused because

Answer 7

1. maximum possible rate of photosythensis is reached
2. limtingfactors such as tmeperature, c02 and water

Question 8

saturation point

Answer 8

the point at
which a substance (e.g. an enzyme)
cannot receive more of another
substance (e.g. a substrate)

Question 9

limiting factor

Answer 9

factor that prevents the rate of reaction from increasing

Question 10

limiting regeant

Answer 10

reactant that
prevents the rate of reaction from
increasing
Chapter 5: PHOTOSYNTHESIS
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This

Question 11

How does wavelengths of light affect rate of photosythensis

Answer 11

Violet ,blue and redwavelengths of light increase the rate of photosythensis because these wavelengths are absorbed by plants

Green and yellow light decreases the rate of photosythensis because green and yellow wavelengths are reflected in green plants, therefore photosytehnsis occurs less effienctly

Question 12

How is the rate of photosythensis affected by temperature

Answer 12

The rate of photosythensis is greatest at the enzymes optimal temperature, however the optimal temperature changes for enzymes based on the environment they have adpated to, eg CAM plants would have a higher optimal temp

When temperatures are too hot enzymes denature so phootsytehnss cannot occur at all

At lower temperature,s there minimised rate of photosytehsnsi due enzymes becoming inactive due to fewer collisions between the enzyme and the substrate

Question 13

How is the rate of photosythensis affected by PH

Answer 13

PH levels above or below the optium will cause enzymes to denature, so photoysthensis will not occur

Enzymes at optimum temperature will allow enzymes to work optimally theroefre high photosythensis rates

Question 14

when is C02 levels/concentraiton low

Answer 14

When the stomata close, C02 concentration is low s

Question 15

How does C02 affect the rate of photosytehnsis

Answer 15

When C02 concentration is high, increased rate of photosynthesis until point X, the saturation point is reached

However too much C02 will cause the cell to be tooPH acidic for the enzymes, therefofe enzymeswill denature resulting rate of photosytenhnsis decreasing

Question 16

Competitive inhibitors

Answer 16

bind to the active site of enzymes to prevent the catalysis of substrates-reversible

Question 17

Non competitive inhibitorsb

Answer 17

non-competitive inhibitors bind to an allosteric site
of an enzyme causing a conformational change to the active site meaning the substrate can
no longer bind.—-irreversible

Question 18

how many G3P are required to create 1 glucose and why

Answer 18

2 g3p is required because 1 g3p contains only 3 carbons and 1 glucose needs 6 carbons

Question 19

Reversible inhibitors (blue)

Answer 19

involve weaker bonds that can be overcome. The reaction can increase if the substrate concentration increases

Question 20

What is light intensity

Answer 20

Light intensity refers to the brightness or level of light present in a given area, which affects the rate of photosynthesis in plants.

Question 21

reading the bellcurve of enzyme activity, how do youread

Answer 21

The beginning and end of the enzyme of the bellcuruve of the enzyme means that complete enzyme denautration has occurred so enzymes fully not functioning, at other times vene at not optimum tmepreuautre still functioning hte higher up the more functioning,

Question 22

Allosteric site

Answer 22

An allosteric site is a specific region on an enzyme where molecules other than the substrate can bind and regulate the enzyme’s activity.

Question 23

what is the problem when alloestirc site changes

Answer 23

whenthe alloesoitrc site changes, the active site hcanges so now the substrate cannot bind because no longer complementary.

Question 24

—changing of allosteriec state

Answer 24

irreversible

Question 25

why does the rate of reacton decrease alot more for non competiive inhibitors than competiive inhibitosr

Answer 25

Non-competitive inhibitors decrease the reaction rate more because they reduce the overall number of active enzymes, making less product no matter the substrate concentration.

Question 26

why is competiive inhibition reversible

Answer 26

The active site remains the same, therefore increasing the substrate concentration can outcompete the competiive inhibitors to bind to the active site of the enzyme

Question 27

why does light affect plants in the same manner

Answer 27

plants have the same light dependent reactions

Question 28

two things can cause the plateau on the CO2 graph:

Answer 28

-The maximum rate of photosynthesis occurs when there is an increase in carbon dioxide (CO2), given that light, water, and temperature conditions are optimal. This is because the enzyme-catalysed systems within the chloroplast are fully saturated and operating as fast as possible. Because enzymes are working at max capacity, further increase in photosynthesise cannot occur so plateau -Limiitng factors like light, temp, water--if there's not enough, plateau occurs

Question 29

why are c4 and cam plants less effected by c02 than c3 plants

Answer 29

C4 and CAM plants have adaptions to decrease photorespiration, so they are able to survive in condiitons with low C02, whereas C3 plants are more reliant on C02 because they have no mechnaismsto decrease photorespriatooon to provide high c02 near rubisco so rubbisco binds to c02 to intiiate photosythensis-specify these mechanisms

Question 30

How do plants prevent water loss

Answer 30

by closing their stomata so that water does not evaporate out of the plant

Question 31

Name 3 reasons why the stomata close

Answer 31

On a hot or windy day there will be more water loss via the stomata so the stomata will close, AND when theres less water in the external environment, the stomata will close

Question 32

Enzyme inhibitors

Answer 32

influence the function of enzymes and, as a result, the rate of photosynthesi the more enzyme inhibitor, the less photosythensis thatoccurs

Question 33

reversible inhibition

Answer 33

enzyme inhibition that involves weaker bonds that can be overcome

Question 34

irreversible inhibition

Answer 34

enzyme inhibition that involves stronger bonds that cannot be broken

Question 35

How do inhibitors affect photosythensis

Answer 35

In general, the presence of inhibitors lowers the rate of photosynthesis. However, the effect of competitive reversible inhibitors can be gradually overcome if the substrate concentration is continually increased Adding more substrate doesn't counteract the effects of irreversible or reversible noncompetitive inhibitors or irrveirbsle comptieivt inhibitorson enzymes, as these inhibitors either permanently deactivate enzymes or change their shape, hindering their function. Consequently, the enzyme activity remains limited even with increased substrate concentration

Question 36

why are C4 and CAM plants left affected by thelimitng factor of water than C3 plants

Answer 36

C4 and CAM plants are less impacted by changes than C3 plants because c4 plants have adapted to decrease photopreisraiotn by photoysthensis in both the mesophyll cells and the bundle sheath cells, whereas CAM plants will photosythensis during both the day and night

Question 37

why is Pep carboxylase not going to bind with oxygen

Answer 37

pep carboxylase is complementary to and therefore will bind to PEP to produce oxaloacetate, therefore lacks a complementary active site to oxygen and will not bind. However RuBisCO can bind to either 02 and C02 depending on availability of these resources.

Question 38

a decrease in temperature from a plants optimal range decreases the rate of photosythensis, why

Answer 38

decreasing temperature means that there is less kinetic energy and therefore, the enzyme and the substrate molecules within the chloroplasts collide less frequently

Question 39

Describe how an increase in light intensity, CO2 concentration, and pH each affect the rate of photosynthesis in a C3 plant. Assume the conditions begin at the optimal and the other factors are unlimited.

Answer 39

Increasing the light intensity increases photosynthesis rate, until the enzyme-catalysed reactions cannot operate any faster and the maximum rate of photosynthesis(saturation point) is reached.1An increase in $$ concentration also increases the reaction rate until the maximum rate is reached.2As photosynthesis rate is greatest when the pH is at the optimal, increasing the pH value beyond this will cause the rate to decrease3as the enzymes within the cells begin to denature.

Question 40

Briefly explain the key differences between C3, C4, and CAM plants, with regard to changes in water availability.

Answer 40

When there is low water avabilty, stomata will close to prvent waterloss. This means CO2 cannot diffuse out, leading to a build up of 02---high 02 concentrations. As c3 plants have not adapted to decrease photorespiration, RuBisCO will bind to 02 instead of C02, intiiating a wasteful process photorespiraiton. Whereas, c4 and cam plants are lessaffetced by water avabilty because thye have mechanisms to decrease photorespiraiton(expalin) and maintain stable photosythensis rates, so theyare only affcted under extreme water stress conditions

Question 41

I have identified why the flasks were sealed in an experiemnt with c3 plants

Answer 41

To ensure that oxygen was not released into the atmosphere, or introduced from the atmosphere, so that the meter recorded only the total amount of dissolved oxygen produced by photosynthesis

Question 42

seed dormancy vs germination